#include <iostream>
#include <list>
using namespace std;

int main()
{
	list<char> coll;      // list container for character elements

	// append elements from 'a' to 'z'
	for (char c='a'; c<='z'; ++c) {
		coll.push_back(c);
	}

	/* print all elements
	 * - while there are elements
	 * - print and remove the first element
	 */
	while (! coll.empty()) {
		cout << coll.front() << ' ';
		coll.pop_front();
	}
	cout << endl;
}
